//
// Random.h
//
// Library: Foundation
// Package: Crypt
// Module:  Random
//
// Definition of class Random.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//
//
// Based on the FreeBSD random number generator.
// src/lib/libc/stdlib/random.c,v 1.25
//
// Copyright (c) 1983, 1993
// The Regents of the University of California.  All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 4. Neither the name of the University nor the names of its contributors
//    may be used to endorse or promote products derived from this software
//    without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//


#ifndef Foundation_Random_INCLUDED
#define Foundation_Random_INCLUDED


#include "Poco/Foundation.h"


namespace Poco
{


class Foundation_API Random
/// A better random number generator.
/// Random implements a pseudo random number generator
/// (PRNG). The PRNG is a nonlinear additive
/// feedback random number generator using 256 bytes
/// of state information and a period of up to 2^69.
{
public:
    enum Type
    {
        RND_STATE_0 = 8, /// linear congruential
        RND_STATE_32 = 32, /// x**7 + x**3 + 1
        RND_STATE_64 = 64, /// x**15 + x + 1
        RND_STATE_128 = 128, /// x**31 + x**3 + 1
        RND_STATE_256 = 256 /// x**63 + x + 1
    };

    Random(int stateSize = 256);
    /// Creates and initializes the PRNG.
    /// Specify either a state buffer size
    /// (8 to 256 bytes) or one of the Type values.

    ~Random();
    /// Destroys the PRNG.

    void seed(UInt32 seed);
    /// Seeds the pseudo random generator with the given seed.

    void seed();
    /// Seeds the pseudo random generator with a random seed
    /// obtained from a RandomInputStream.

    UInt32 next();
    /// Returns the next 31-bit pseudo random number.

    UInt32 next(UInt32 n);
    /// Returns the next 31-bit pseudo random number modulo n.

    char nextChar();
    /// Returns the next pseudo random character.

    bool nextBool();
    /// Returns the next boolean pseudo random value.

    float nextFloat();
    /// Returns the next float pseudo random number between 0.0 and 1.0.

    double nextDouble();
    /// Returns the next double pseudo random number between 0.0 and 1.0.

protected:
    void initState(UInt32 seed, char * arg_state, Int32 n);
    static UInt32 goodRand(Int32 x);

private:
    enum
    {
        MAX_TYPES = 5,
        NSHUFF = 50
    };

    UInt32 * _fptr;
    UInt32 * _rptr;
    UInt32 * _state;
    int _randType;
    int _randDeg;
    int _randSep;
    UInt32 * _endPtr;
    char * _pBuffer;
};


//
// inlines
//
inline UInt32 Random::next(UInt32 n)
{
    return next() % n;
}


inline char Random::nextChar()
{
    return char((next() >> 3) & 0xFF);
}


inline bool Random::nextBool()
{
    return (next() & 0x1000) != 0;
}


inline float Random::nextFloat()
{
    return float(next()) / 0x7FFFFFFF;
}


inline double Random::nextDouble()
{
    return double(next()) / 0x7FFFFFFF;
}


} // namespace Poco


#endif // Foundation_Random_INCLUDED
